GPS location-receiving devices are commonly used in vehicles to provide the driver with location information and a route to a desired destination. The GPS receiver receives location-indicating signals from a constellation of GPS satellites, periodically updating the current location as the vehicle travels toward its destination. A GPS receiver system can also be used to geolocate stolen vehicles. The geodetic (location) data is sent back to a system computer for processing and completing the vehicle recovery process.
There are presently two systems for use in stolen vehicle recovery, referred to as the OnStar system and the LoJack system. A brief description of the operational features of these systems is presented below.
OnStar combines the services and functionality of emergency service providers, wireless telephones, and satellite communication technologies to provide emergency services to subscribers and allow them to stay connected to the system while on the road. The vehicle-based portion of the system is powered by the vehicle's battery. If the battery is damaged or disconnected, the system ceases operation. OnStar is a subscription-based communication system that provides for in-vehicle security, hands free calling, navigation, and remote diagnostics systems throughout North America. If GPS location information is lost, as provided by signals from the constellation of GPS satellites, navigation is not available through the OnStar system.
The LoJack system is a stolen vehicle recovery system comprising a small (hidden in the vehicle) radio transceiver capable of operating even after the vehicle battery has been disconnected. When a vehicle equipped with a LoJack system is stolen, the vehicle owner reports the incident to the police, and the LoJack unit in the vehicle is triggered by a signal sent from a LoJack control center. When activated, every tracking unit-equipped police car within a 2-3 mile radius is automatically alerted that the vehicle is near responsive to the vehicle transceiver. The system combines radio frequency (RF) technology with angle of arrival (AOA) technology to locate the vehicle. The LoJack signal propagates through structural walls, allowing the vehicle to be “seen” when hidden from view in garages or buildings. Obviously, it may take many hours for a LoJack-equipped vehicle to be located.
FIG. 1 depicts operation of one prior art system comprising a GPS receiver 10 onboard a vehicle 12. A long range location-requesting signal, for example from a GSM mobile phone, is received at an antenna 14 and carried to a system controller 16, which includes transceiver hardware that is not separately depicted. The system controller 16 determines the current location from the GPS receiver 10 and transmits a location response signal via the transceiver from an antenna 18.